With an upcoming tubing trip on the Delaware river I started to research
floating radios and came across this site.
After seeing his floating cooler radio I knew I had to build one.
Lucky for me I have a bunch of left over fiberglass supplies in
the basement so minus the audio equipment it should be a relatively
cheap project. Only problem is I only have about 2 weeks to build
it. Jumping right in I ordered the audio equipment:

Lets get building. The base is made out of PVC pipe because
it is cheap, light, and holds air. I figured this would create a 2
chambered design so even if the fiberglass part took on water it still
may float.
Once the pipe was glued together I screwed a couple of pieces of 1/4
inch plywood to the pipe to create the bottom of the raft. In trying
to make this project as cheap as possible I just used a piece of scrap
plywood I had in the basement. A larger single piece would have been
better, but this will work.

Time to break out the fiberglass mat. I actually hate working
with chopped mat, but it does build up quick and I have a huge roll
of it.
One layer on the top and one layer on the bottom.

For the sides I made a frame using some 1X2 and
foam insulation. After taping the foam panels in place it was time
for more fiberglass.

For the corners I tape pieces of poster board to the foam
panels and laid fiberglass over them.

I used an angle grinder and a cut off wheel to open up
the top. Then I used a sanding disk to knock down any of the high
spots. This also reveled a few holes in the hull.

I wasn't looking for a surface so smooth you could paint
it, but chopped mat just looks looks like shit. A quick coat of bondo
and some sanding made it look much better.

After smoothing it out I went and covered it with some
fiberglass cloth. Cloth is much easier to work with and lays down
flat.

It was time for the moment of truth, the float test. Besides
the fact that it hardly fit in the pool I purchased and that it
tore a hole in the top two air cambers, the pool still held water
and the radio floated. I completely over estimated how big this thing
needed to be to float. I stood in the radio and it barely sunk down
in the water.

To power the amp and speakers I am using an old truck battery.
I used some 1X2's, 2 pieces of all thread and a piece of scrap aluminum
angle. The all thread screws into T-nuts that are mounted to the bottom
of the 1X2's. A little lock tight keeps them from spinning when you
tighten the wing nuts. You can see where I had to flatten the aluminum
for the wing nut to clear. It may not be pretty but it works.

Next up was cutting the holes for the speakers and cutting
a piece of 1/4 inch plywood for the lid. Here again I am using T-nuts
mounted in the underside of the frame to give the all thread something
to thread into.

Next up was covering the
top section of the radio in red/black carbon. I only had enough laying
around to cover the top section so I just painted the bottom black.
I didn't have a piece large
enough to cover the top section in one piece, so I seamed together
4 pieces. Down each corner are 2 pieces of black cloth tape covering
the seams.

Next up was lid. The first thing I did was cover the top
section in tin foil to keep the blue painters tape from sticking
to the radio. Once the foil was down I applied the painters tape.
You will notice I created a little ledge to catch any excess resin
from running down the side of the radio. The masking tape line is
so I can see where to put the fiberglass and have a relatively strait
line to follow. Fiberglass cloth wets out almost clear so the tape
line stays visible.

With the shell done it was time to wire everything up.
The amp is mounted on a make shift amp rack to keep it off the floor
and out of any water that may leak in. The amp is rated
50W RMS x 2 channels @ 4 ohms (continuous); 75W RMS x 2 channels @ 2 ohms (continuous),
so I decided to wire the each pair of speakers in parallel. This effectively
turns each pair of speakers into a single 2 ohm speaker which gets 75W
from the amp. Over all each speaker will receive about 37.5W. The amps
remote turn on line is connected to a water proof switch mounted outside
the hull next to one of the speakers. Finally I mounted the water proof
case on the outside of the hull. The ipod to RCA line connects the iPod
to the amp. The volume control on the iPod and the gain on the amp control
the volume. I wouldn't call the project done, but it is good enough
for now. The radio hits the water tomorrow morning.

09/11/10 Update
I am happy to report that the radio survived its first tubing trip. It
was on the water for about 6 hours and it did fine. When we reached
the campsite is was dark so I didn't get a chance to open it up and
see how much water it took on, but in the morning there was maybe 1/8"
of water in the bottom. Tubing season is pretty much over, but that
doesn't mean I can get ready for next year. I learned from this trip
that the speakers need more power. With the current set up each speaker
is only getting about 37 watts and if you where more than 10-15ft way
it was hard to hear. The upgrades I have planed include, a bigger amp
to power the 4 existing speakers, a 10" sub woofer, an amp for the
sub, a battery power indicator, and some straps to carry it.

Final updates until next year. The new/second amp has been installed. It is a
MR800 Boss Marine 2 Channel Amp 800 Watts that I picked up from www.crispdeals.com. The amp is rated
125 RMS x 2 channels @ 4 ohms (continuous); 225W RMS x 2 channels @ 2 ohms (continuous),
again the speakers are wired in parallel. This effectively
turns each pair of speakers into a single 2 ohm speaker which gets 225W
from the amp. Over all each speaker will receive about 112.5W, which is a nice step up from the 37.5W they were getting. We will see how it does on the water, but inside the house it seems much louder than before.

With old amp is now powering a 10 inch Boss Marine sub. With the amp bridged the sub is getting 175W RMS @ 4 ohms (continuous).

Because I have no idea how much water the radio took on while floating I decided to install a SeaSense Bilge Pump, float switch, and check valve. I think it is going to take a fair amount of water to set off the switch, so if I ever see it running I will know that the radio does take on a lot of water.

I needed some where to store this beast so I welded up a cradle and attached a winch to the ceiling in the garage. The rope is a back up just incase the winch lets go or slowly unwinds over time.